1. Field of Invention
The present invention relates to a plug type connector for coupling wiring within a vehicle such as an automobile and, more particularly, relates to the double engagement structure of a coupling terminal in a plug type connector which ensures that the coupling terminal is quickly and surely inserted into and engaged with the housing of the plug type connector.
2. Related Art
In a vehicle such as an automobile in which various kinds of electronic devices are mounted, the conventional plug type connector for connecting wire harness wired among the electronic devices is disclosed in U.S. Pat. No. 5,624,284, for example.
As shown in FIGS. 11 and 12, a housing 61 forming a part of the conventional plug type connector is received in a groove (not shown) provided at a sliding portion 51 along the longitudinal direction thereof. The sliding portion is provided with movable contact rooms 52 of a concave shape on both side surfaces thereof. The sliding portion is further provided on each of both sides thereof with a plurality of table portions 53 which are protrusively provided and separated from one another with a space corresponding to the width of each of a tongue shaped elastic first engagement piece 57a and a tongue shaped elastic second engagement piece 57b whose one ends are supported by the both side surfaces of a coupling terminal 54.
The upper end surface of the table portion 53 has a function as a first engagement portion 55 which engages with the other end of the first engagement piece 57a serving as a free end. In contrast, the table portion 54 is provided at the lower end of the side surface thereof with a projection portion 56 which avoids an electric wire fastening portion 58 and abuts against the bottom surface of the coupling terminal 54 so as to be able to lift the coupling terminal 54 in accordance with the movement of the slide portion 51 toward the direction shown by an arrow b.
Further, as shown in FIG. 12, a fixing contact room 62 is formed in a concave shape at the side wall of the housing in opposite to the side wall of the sliding portion 51. The lower end surface of the fixing contact room has a function as a second engagement portion 63 which engages with the other end of the second engagement piece 57b serving as a free end. The second engagement portion 63 is positioned at the portion slightly above the first engagement portion 55 arrived at its maximum upper limit.
In the case of assembling the coupling terminal 54 into the housing 61, firstly the slide portion 51 is slid along a groove (not shown) provided at the housing 61 so as to cross the housing and then inserted at a predetermined standby position of the housing in advance. Then, the coupling terminal 54 is entirely pressed into the housing toward the direction shown by an arrow a while sliding the first engagement piece 57a into the space between the table portions 58 of the sliding portion 51 and also sliding the second engagement piece 57b on the lower wall of the second engagement portion 63.
The first engagement piece 57a thus passed through the space between the table portions 58 is entirely housed within the movable contact room 52 together with it's the other end. However, since the fixing contact room 62 is positioned above the movable contact room 52, the other end of the second engagement piece 57b is not housed within the fixing contact room 62, so that the elastically deformed configuration of the other end of the second engagement piece is maintained almost in a straight shape.
In this state, the sliding portion 51 is slid and pushed linearly to a predetermined position toward the direction shown by the arrow b in FIG. 11 thereby to engage the first engagement portion 55 with the other end of the first engagement piece 57a. Thereafter, the sliding portion 51 is further slid and pushed linearly to the predetermined position toward the direction shown by the arrow b, whereby a wedge portion 53a protrusively provided at the lower end surface of the table portion 58 moves straightly in such a manner that the protruded end surface of the wedge portion slides in a contacted manner on the protruded end surface of other wedge portion (not shown) of the bottom surface of the housing provided in opposite to the wedge portion 53a.
As a result, the sliding portion 51 moves upward. In this respect, on the way where the sliding portion moves upward to the position shown by a phantom line in FIG. 12, firstly the projection portion 56 abuts against the bottom surface of the coupling terminal 54, then soon moves the coupling terminal 54 upward, and thereafter the entirety of the coupling terminal including the other end of the second engagement piece 57b is housed within the fixing contact room 62.
Thus, the other end of the first engagement piece 57a and the other end of the second engagement piece 57b are positioned to the same level by the first engagement portion 55 and the second engagement portion 63, respectively. Therefore, the stress such as pulling force etc. is equally distributed and the projection portion 56 prevents the coupling terminal 54 from being dropped.
However, according to the aforesaid conventional plug type connector, when the initial assembling stage is terminated in a state that a part of the first engagement piece 57a of the coupling terminal 54 is remained within the space between the table portions 58, the part of the first engagement piece 57a is pushed in toward the lateral direction by the table portions 58 and remarkably deformed in the succeeding assembling stage for linearly sliding the sliding portion 51 in the direction shown by the arrow b.
Thus, the other end of the first engagement piece 57a can not be engaged with the first engagement portion 55. Therefore, the conventional plug type connector in a sate that the assembling process of the coupling terminal 54 has been completed has a problem that the first engagement piece 57a and the second engagement piece 57b can not be fixed with an equal engagement force.
Further, since the conventional plug type connector does not have a means for effectively detecting the abnormal insertion of the coupling terminal 54 in the initial assembling state thereof, the coupling terminal 54 is assembled within the housing in the aforesaid unstable state.
Thus, when the a pin or a blade serving as a male type terminal of a partner-side connector is inserted between elastic contact pieces 59 disposed at the tip end portion of the coupling terminal 54, there arises a problem that the coupling terminal 54 can not withstand against the insertion force of the male type terminal and so the entirety thereof is abnormally deformed or dropped out.